Gas Produced Water Treatment Research Articles

Fertilizer-driven FO and MD integrated process for shale gas produced water treatment: Draw solution evaluation and PAC enhancement

It is a great challenge for effective treatment of shale gas produced water (SGPW), a typical industrial wastewater with complex composition. Single forward osmosis (FO) or membrane distillation (MD) process has been widely used for desalination of SGPW, with membrane fouling not well addressed. Fertilizer draw solution (DS) with high osmotic pressure is less likely to cause FO fouling and can be used for irrigation. An integrated process using fertilizer-driven FO (FDFO) and MD process was proposed for the first time for SGPW treatment, and characteristics of fertilizer DS and powdered activated carbon (PAC) enhancement were assessed. The DS using KCl and (NH4)2SO4 had high MD fluxes (36.8–38.8 L/(m2·h)) and low permeate conductivity (below 50 μS/cm), increasing the contact angle of the MD membrane by 113 % than that without FO, while the DS using MgCl2 and NH4H2PO4 produced a lower reverse salt flux (0.9–3.2 g/(m2·h)). When diluted DS was treated using PAC, the MD permeate conductivity was further reduced to 35 μS/cm without ammonia, and the membrane hydrophobicity was maintained to 71–83 % of the original. The mechanism of the FDFO-MD integrated process for mitigating MD fouling and improving permeate quality was analyzed, providing guidance for efficient SGPW treatment.

Gravity-driven membrane integrated with membrane distillation for efficient shale gas produced water treatment

Substantial volumes of hazardous shale gas produced water (SGPW) generated in unconventional natural gas exploration. Membrane distillation (MD) is a promising approach for SGPW desalination, while membrane fouling, wetting, and permeate deterioration restrict MD application. The integration of gravity-driven membrane (GDM) with MD process was proposed to improve MD performance, and different pretreatment methods (i.e., oxidation, coagulation, and granular filtration) were systematically investigated. Results showed that pretreatment released GDM fouling and improved permeate quality by enrich certain microbes’ community (e.g., Proteobacteria and Nitrosomonadaceae), greatly ensured the efficient desalination of MD. Pretreatment greatly influences GDM fouling layer morphology, leading to different flux performance. Thick/rough/hydrophilic fouling layer formed after coagulation, and thin/loose fouling layer formed after silica sand filtration improved GDM flux by 2.92 and 1.9 times, respectively. Moreover, the beneficial utilization of adsorption-biodegradation effects significantly enhanced GDM permeate quality. 100 % of ammonia and 53.99 % of UV254 were efficiently removed after zeolite filtration-GDM and granular activated carbon filtration-GDM, respectively. Compared to the surged conductivity (41.29 μS/cm) and severe flux decline (>82 %) under water recovery rate of 75 % observed in single MD for SGPW treatment, GDM economically controlled permeate conductivity (1.39-19.9 μS/cm) and MD fouling (flux decline=8.3 %-27.5 %). Exploring the mechanisms, the GDM-MD process has similarity with Janus MD membrane in SGPW treatment, significantly reduced MD fouling and wetting.

Application of Circular Economy in Oil and Gas Produced Water Treatment

The circular economy (CE) is a promising model in industrial waste management, offering viable long-term resource sustainability. The rising costs of the oil and gas industry make circularity a reliable approach for saving materials, money, and energy. In recent years, attention has risen to the need to apply CE within oil and gas produced water (PW) treatment. The most common treatment practice for PW is based on mechanical treatment, with optional disposal of treated water into deep wells. However, this procedure consumes a lot of energy, increases operational costs, and causes environmental risks. This research aims to propose sustainable treatment technology promoting circularity by introducing a novel nature-based solution to treat PW. The main research objective is to develop a circular model for PW treatment by investigating the treatment of PW using constructed wetlands (CWs) to sustainably reduce the amount of waste in oil and gas fields. Additionally, investigate the use of industrial wastes as filtration materials for CW systems. In this study, eight different laboratory-scale CWs models were designed and tested. The CWS operated in two different types of flow directions: vertical (VF) and horizontal flow (HF). The main filter media for the CW system included aggregates, activated carbons, plastic, and shredded tires. The study investigated the removal rates of Total suspended solids (TSS), Total dissolved solids (TDS), Oil and Grease (OG), and Total Petroleum Hydrocarbon (TPH) from the PW. Testing the CWs, it was found that the results of the PW treatment were promising, with the potential for more future shredded tires and plastic applications. All systems were effective at removing contaminants from produced water, with the highest recorded removal efficiencies of 94.8% TSS, 33.7% TDS, 90.2% OG, and 98.4% TPH. The research results were efficient and promoted the circular use of CW in PW treatment in addition to the possibility of reusing the treated effluent in agriculture and irrigation.

Sustainability and resilience-oriented prioritization of oil and gas produced water treatment technologies: A novel decision support system under circular intuitionistic fuzzy set

The transition towards sustainable water resources management (SWRM) needs for employing proper treatment technologies for pollutant removal from polluted waters and ensures the development in the dimensions of sustainability (including environmental, economic, technological, and social aspects) and resilience in the region. Utilizing these technologies for treating waters produced by oil and gas fields in Behbahan city (in the southwest of Iran) is considered. The oil and gas produced water treatment technologies (OGPWTTs) can assist local authorities, governments, investors, and developers to reduce climate change, environmental pollution, the threats related to food security and public health, and construct sustainable communities. With the aim of balance between the issues in the context of sustainability and resilience policies, 20 criteria (principles) are considered. The research takes into consideration the applicability of a novel decision support system namely circular intuitionistic fuzzy set (CIFS)-based combinative distance-based assessment (CODAS). The CIFS-CODAS can be used to choose suitable technologies in a sustainable mode, considering the principles related to sustainability and resilience aspects. It comprises various technologies for the treatment of produced water from oil and gas extraction and production activities and prioritizes technologies for three steps of primary, secondary, and tertiary treatments as follows, respectively: API gravity separator technology, Adsorption technology, and MPPE technology. This work can be valuable and practical to manage produced water and help to achieve the purposes of environmental sustainability and a green future in the oil & gas industry.

Hybrid resin composite membrane for oil & gas produced water treatment

In this work, a hybrid resin composite membrane was successfully synthesized from a phenyl epoxy/poly (vinyl pyrrolidone)/Fe3O4 resin composite and characterized using a scanning electron microscope (SEM). Performance characteristics such as concentration factor, the flow rate, and permeate flux of the synthesized hybrid resin membrane were investigated. The concertation factor was changed through the experiment from 1 to 1.6. The flow rate changed from 2.5 l/h at the beginning of the experiment to 1.05 l/h by the end of the experiment. The permeate flux was equal to 8.9 l/(m2h) at the beginning of the investigation. It was noticed that the permeate flux decreased over time to 3.76 l/(m2h). In addition, the hybrid resin composite membrane was efficiently used for treating petroleum-produced water (PPW) as an alternative to chemical scale inhibitors. The results showed that the proposed treatment system could successfully remove most scale-forming cations and anions from the PPW. Combining the new prepared resin with membrane could remove several cations and anions from OFPPW at rates ranging from 75% (for Strontium) to 97% (for Barium), while the Iron was 100% removed. Thus, the treated water effluent could be reused safely as injection water in the petroleum production process without concern for forming Barium sulfate and Dolomite scales in the used water.

Optimization of mobile oil and gas produced water treatment unit deployment logistics to achieve economic feasibility

• Techno-economic assessment of on-site produced water desalination . • The concept of capacity factor is applied to desalination where demand is variable. • Systems level optimization of mobile desalination module deployment. • Multi-objective optimization considering economics and water reclamation . Development of unconventional oil and gas wells has resulted in large volumes of wastewater that require careful handling to minimize environmental risks. Common practice is to truck the wastewater from well sites to Environmental Protection Agency Class II underground injection control wells. Recently, on-site wastewater treatment followed by surface water discharge for downstream reuse has emerged as being viable. This work applies the concept of capacity factor to on-site oil and gas wastewater treatment. By accounting for intermittent wastewater treatment demands at individual well sites, the attributes of optimal on-site packaged treatment unit deployment logistics for oil and gas wastewater management are determined. The attributes considered are packaged unit capacity, deployment length, and the number of units deployed. This work explores different deployment logistics in Weld County, Colorado, United States to determine a set of Pareto optimal logistics from a techno-economic and environmental perspective. Ultimately, there exists a Pareto frontier because the marginal cost of water treatment increases as reuse increases beyond a critical threshold, in Weld County where the cost of business as usual operation (injection) is constant at $7.68 per m 3 produced. Generally, optimal deployment logistics, when accounting for capacity factor, utilize packaged wastewater treatment units sized at 100 m 3 per day capacity with deployment location reevaluated monthly. This article focuses on the importance of capacity factors at on-site treatment units and presents limitations of the study and the opportunity for the application of the presented methods to other case studies through utilization of the open-source model produced in this work.

Optimization-based modeling and economic comparison of membrane distillation configurations for application in shale gas produced water treatment

Membrane distillation (MD) is an emerging membrane technology with great potential for treatment of hypersaline wastewater generated by unconventional (shale) oil and gas reservoirs. However, the low energy efficiency of this technology makes the operating cost of MD systems relatively high, especially in the absence of waste heat. There are several MD configurations with inherent advantages and disadvantages and varying performance. As such, there is a need for thermo-economic optimization of MD systems in a systematic manner to assess their economic performance. We present an optimization framework to model and compare the performance of six MD configurations (DCMD, AGMD, PGMD, CGMD, SGMD, and VMD) in continuous recirculation mode for treatment of hypersaline wastewater. The optimization results show that AGMD with small gap size operated at low stream Reynolds number outperforms all other configurations with treatment cost of 4.57 US $/m3 of feed. However, restricting the system design to more practically relevant operating conditions, such as higher Reynolds number and larger gap size, diminishes the cost superiority of AGMD over other configurations. We also observed that treatment cost using PGMD configuration approaches those of CGMD and DCMD, particularly when modules with small gaps are used.

Hole-Type Spacers for More Stable Shale Gas-Produced Water Treatment by Forward Osmosis.

An appropriate spacer design helps in minimizing membrane fouling which remains the major obstacle in forward osmosis (FO) systems. In the present study, the performance of a hole-type spacer (having holes at the filament intersections) was evaluated in a FO system and compared to a standard spacer design (without holes). The hole-type spacer exhibited slightly higher water flux and reverse solute flux (RSF) when Milli-Q water was used as feed solution and varied sodium chloride concentrations as draw solution. During shale gas produced water treatment, a severe flux decline was observed for both spacer designs due to the formation of barium sulfate scaling. SEM imaging revealed that the high shear force induced by the creation of holes led to the formation of scales on the entire membrane surface, causing a slightly higher flux decline than the standard spacer. Simultaneously, the presence of holes aided to mitigate the accumulation of foulants on spacer surface, resulting in no increase in pressure drop. Furthermore, a full cleaning efficiency was achieved by hole-type spacer attributed to the micro-jets effect induced by the holes, which aided to destroy the foulants and then sweep them away from the membrane surface.

Efficient oil/saltwater separation using a highly permeable and fouling-resistant all-inorganic nanocomposite membrane

Although it is still a great challenge, developing oil-/water-separating membranes that combine the advantages of high separation efficiency, salty environments tolerance, and fouling resistance are highly demanded for marine oil spill cleanups and oil-/gas-produced water treatment. Here, we report a new type of all-inorganic nanostructured membrane, which is composed of titanate nanofibers and SiO2 particulate gel for efficient and stable oil/saltwater separation. The nanoporous and interconnected network structure constructed with titanate nanofibers is the key to ensure the high separation efficiency and high water flux of the new membrane. The SiO2 gel is used as a binder to offer mechanical flexibility and integrity for this type of all-inorganic membrane. The new membrane displays a high oil/water separation efficiency of above 99.5% with oil content in treated effluent lower than US environmental discharge standards (42 ppm) and high water permeation flux of 1600 LMH/bar under low operation pressure. The new membrane also demonstrates outstanding durability in the environment of different salinities, and it has a good resistance for oil fouling due to its excellent underwater superoleophobicity with an oil contact angle above 150 °. Most importantly, the underwater superoleophobic properties can be well maintained after being repeatedly reused. The excellent environmental durability, oil-fouling resistance, high separation efficiency, and facile fabrication process for this new type of membrane render great potential for industrial application in treating produced water.

Benefits of polymeric membranes in Oil and Gas produced water treatment

Abstract Falling oil prices and increased environmental concern lead oil and gas companies to reinject produced water(PW) to reduce both their water management costs and environmental footprint. Membrane processes are an attractive opportunity because they generate a higher quality effluent than conventional PW treatment technologies at a competitive cost. The objective of the study was to compare the performances of ten membranes to treat PW and identify which of the structural and operational characteristics of the membranes are the success factors to ensure cost-effective, long-term and reliable operation. In oil and gas applications, ceramic filtration media is often preferred owing to its high structural robustness. Nevertheless, polymeric membranes offer the benefits of being less expensive and result in a lower footprint and weight. Tests using real oilfield PW were run to assess and compare ten membranes according to their oil rejection rate, permeability, resistance to fouling, life expectancy and resistance to ageing. All membranes tested achieved more than 99% removal of insoluble oil versus 80–85% for conventional technologies. The permeability over time and resistance to fouling were used to identify the most reliable and cost-effective membranes. The robustness of polymeric membranes was confirmed based on good resistance to ageing.

Osmotically enhanced dewatering-reverse osmosis (OED-RO) hybrid system: Implications for shale gas produced water treatment

Managing shale gas produced water (SGPW) is one of the greatest challenges for shale gas industry due to its high salinity and water volume. Osmotically enhanced dewatering (OED) has great potential for treating SGPW because of its higher water recovery and lower energy consumption. This study systematically investigated the effects of operating conditions on OED performance through numerical simulation of membrane modules. The simulation results first showed that OED achieved higher water recovery over forward osmosis (FO) due to less internal concentration polarization (ICP). Water recovery could be higher with decreasing feed flow fraction, increasing normalized membrane area, and increasing hydraulic driving force fraction. It was also demonstrated that OED-RO hybrid process was able to yield more water with similar energy efficiency as one-stage RO, for SGPW of 28.5 g/L total dissolved solids (TDS) under realistic conditions considering inefficiency associated with pump and energy recovery device (ERD). Lastly, to validate our findings, OED experiments were performed with pre-treated real SGPW as a feed solution, and exhibited good agreement with the simulation results. Specifically, water recovery was achieved up to 67% with a high rejection rate of over 97% for most ions at a hydraulic pressure of 30 bar. Our modeled and experimental observations suggest that the OED-RO process can be an energy-efficient process in concentrating high salinity wastewater.

Analysis of an osmotically-enhanced dewatering process for the treatment of highly saline (waste)waters

The dewatering of highly saline (waste)waters by typical osmotic membranes, such as reverse osmosis (RO) or forward osmosis (FO), was significantly improved by a novel process in which an osmotic pressure gradient across the membrane is eliminated or reduced by increasing osmotic pressure in the permeate side. In this work, the concept of an osmotically enhanced dewatering (OED) process was fundamentally analyzed via conceptual modeling and verified experimentally under various hydraulic and osmotic pressure conditions. No or less osmotic gradient across the membrane resulted in higher water recovery than RO. Larger water flux was also produced than FO because the loss of osmotic driving force by internal concentration polarization (ICP) was greatly reduced. For instance, a series of experiments demonstrated that water flux of 1.2 LMH was obtained at low hydraulic pressure of 15bar when a feed of 2.4M NaCl was dewatered by the OED process. In addition, membrane characteristics (A, B, S) were optimized by modeling, and further examined experimentally using typical NF and FO membranes. Lastly, less reverse solute diffusion ensured a product of high quality after dewatering, suggesting that this process can be applied to not only highly saline shale gas produced water treatment, but also protein and pharmaceutical enrichment.

Coal seam gas produced water treatment by ultrafiltration, reverse osmosis and multi-effect distillation: A pilot study

This study evaluates the technical feasibility of a pilot treatment train of ultrafiltration, reverse osmosis (RO), and multi-effect distillation (MED) for coal seam gas (CSG) produced water treatment. A total of 12,000L of CSG produced water was processed from the Gloucester Basin in New South Wales (Australia). The results demonstrate the technical feasibility to obtain an overall clean water recovery of 95% and a final brine containing mostly sodium bicarbonate up to of 48g/L. Stable operations of the pilot RO and MED systems at 76% and 80% recovery, respectively, were achieved. The results show that anti-scalant addition could effectively prevent scaling during MED operation. Mass balance analysis and analytical measurement suggest that precipitation of calcium, magnesium and silica might have occurred. Indeed, mineral deposition on the sight glass of the MED evaporative chamber became visible after 3days of continuous operation. However, no evidence of mineral precipitation or scaling could be observed on the evaporative tubes of the MED system. In addition, the mineral deposition on the sight glass was completed removed by chemical cleaning at the end of the pilot evaluation program. The obtained RO permeate and MED distillate were of high quality and could be blended with UF filtrated CSG produced water for irrigation to reduce the treatment demand.

Shale gas produced water treatment using innovative microbial capacitive desalination cell

The rapid development of unconventional oil and gas production has generated large amounts of wastewater for disposal, raising significant environmental and public health concerns. Treatment and beneficial use of produced water presents many challenges due to its high concentrations of petroleum hydrocarbons and salinity. The objectives of this study were to investigate the feasibility of treating actual shale gas produced water using a bioelectrochemical system integrated with capacitive deionization—a microbial capacitive desalination cell (MCDC). Microbial degradation of organic compounds in the anode generated an electric potential that drove the desalination of produced water. Sorption and biodegradation resulted in a combined organic removal rate of 6.4mg dissolved organic carbon per hour in the reactor, and the MCDC removed 36mg salt per gram of carbon electrode per hour from produced water. This study is a proof-of-concept that the MCDC can be used to combine organic degradation with desalination of contaminated water without external energy input.